Linear properties of the reverse shear Alfvén eigenmode (RSAE) in a well-diagnosed DIII-D tokamak experiment (discharge #142111) are studied in gyrokinetic particle simulations. Simulations find that a weakly damped RSAE exists due to toroidal coupling and other geometric effects. The mode is driven unstable by density gradients of fast ions from neutral beam injection. Various damping and driving mechanisms are identified and measured in the simulations. Accurate damping and growth rate calculation requires a non-perturbative, fully self-consistent simulation to calculate the true mode structure. The mode structure has no up–down symmetry mainly due to the radial symmetry breaking by the density gradients of the fast ions, as measured in the experiment by electron cyclotron emission imaging. The RSAE frequency up-sweeping and the mode transition from RSAE to TAE (toroidal Alfvén eigenmode) are in good agreement with the experimental results when the values of the minimum safety factor are scanned in gyrokinetic simulations.
在诊断良好的DIII-D托卡马克实验（放电#14211）中，反向剪切阿尔芬本征模（RSAE）的线性特性通过回旋动理学粒子模拟进行了研究。模拟发现，由于环向耦合及其他几何效应，存在一个弱阻尼的RSAE。该模由中性束注入产生的快离子密度梯度驱动不稳定。模拟中识别并测量了各种阻尼和驱动机制。精确的阻尼率和增长率计算需要非微扰、完全自洽的模拟来获得真实的模结构。该模结构不具有上下对称性，这主要源于快离子密度梯度引起的径向对称性破缺，与实验中通过电子回旋辐射成像测得的结果一致。当在回旋动理学模拟中扫描最小安全因子值时，RSAE频率的上扫及从RSAE到环向阿尔芬本征模（TAE）的模转变与实验结果吻合良好。